Date of Award
12-1-2025
Degree Name
Master of Science
Department
Physics
First Advisor
Talapatra, Saikat
Abstract
High-entropy alloys (HEAs) based materials have been investigated in this thesis to assess their viability as electrode materials for Electrochemical Double Layer Capacitors (EDLCs). Two different types and morphologies of HEAs were used as electrode material: one of them was FeCoNiCrAg (FCNCA) in the bulk form, and the other was FeCoNiCrMn (FCNCM) in powder form.To investigate the electrochemical performance of these HEAs, EDLC devices were fabricated using an aqueous 6 M KOH electrolyte in a two-electrode system, employing Cyclic Voltammetry (CV), Galvanostatic Charge-Discharge (GCD), and Electrochemical Impedance Spectroscopy (EIS) techniques. One EDLC device was assembled with two bulk pieces of FCNCA as electrodes, which demonstrated good capacitive behavior with ~5.64mFcm^(-2) areal capacitance at 10mVs^(-1). Another device was assembled with electrodes, fabricated using a composite of Multiwall Carbon Nanotube (MWNT) and FCNCM powder. The fabrication of the MWNT–FCNCM composites was necessary since it was difficult to fabricate free-standing electrodes from the as-received FCNCM powder. The areal capacitance was found to be 29.57 mFcm^(-2) at 10mVs^(-1)scan rate. A single device was also prepared only with MWNT electrodes in order to compare the capacitive behavior with the composite device. The MWNT device provides an areal capacitance of ~41.18mFcm^(-2) at 50mVs^(-1)scan rate. The specific energy of the composite device was 3.3×10^(-3) Wh〖kg〗^(-1) and specific power of 1.19 W〖kg〗^(-1) at 0.01 mA current. Overall, these findings show that HEAs can be utilized as the electrode material for EDLCs; however, further refinement of the materials and/or the structure of the electrode needs to be investigated in order to have higher values of capacitance. While the HEA-MWNT composite electrodes' performance was not better than the MWNTs electrodes, the study was informative in demonstrating how careful design of HEA composition, morphology, and integration methods will influence EDLC performances. This research emphasizes the importance of additional HEA optimizations in the future to enable next-generation supercapacitor materials.
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